There are over 40,000 chemical compounds registered for use in Australia; however, very few of these have been monitored in aquatic receiving environments. This study combined chemical, in vitro, in vivo and in situ techniques to determine the extent of endocrine disruption in fish living in Australian rivers.

PhD Thesis completed by Philip David Scott in April 2014.

Every day, Australians produce ~5 billion litres of wastewater, which contains a cocktail of chemicals. Industries that discharge wastewater are required to assess chemical risks to the receiving environments by conducting whole animal direct toxicity assessments (DTAs), which are expensive and pose an ethical dilemma. Our preliminary research shows that new in vitro bioassays provide an ethical and cost effective alternative that could be incorporated into DTA programs if their ecological relevance can be demonstrated. This project will develop and validate a new and internationally significant suite of in vitro bioassays for incorporation into DTA programs, leading to more ethical, cost effective and improved environmental protection.

The standards for recycling stormwater are higher for drinking water than for non-potable reuse such as agricultural or urban irrigation. The Australian Drinking Water Guidelines (ADWG) inform regulations that ensure the removal of infectious pathogens and polluting chemicals from potable water, whereas the Australian Guidelines for Water Recycling (AGWR) ensure that non-potable recycled water does not pose a risk to human health. Compliance with these Guidelines often requires quantitative risk assessment of stormwater catchments, but this is an expensive and resource-intensive process. This research developed a ‘Chemical Hazard Assessment of Stormwater Micropollutants’ (CHASM) desktop tool to assess the suitability of stormwater for various potable and non-potable uses before commencing an expensive risk assessment, and to guide design of optimal and targeted monitoring and measuring programmes for chemicals of concern in any given catchment. Basic information about each of four Australian stormwater catchments (including size, land-use, and surface types) was entered into CHASM Excel spreadsheets. The tool utilises a database to generate a list of likely pollutants for that catchment, and optimal locations and times for monitoring. The CHASM tool proved reliable and easy to use.

Compliance with the Australian Guidelines for Water Recycling ensures that recycled wastewater does not present a health risk due to infectious pathogens or disease-causing chemicals. Many pathogens in wastewater are inactivated by disinfection treatments such as chlorination, but this causes a problem when disinfectants react with nitrogen compounds in wastewater and form Disinfection By-Products (DBPs), some of which pose a health risk. This research collected samples from four wastewater treatment plants (WWTPs) with different treatment methods and climate zones. A comprehensive and innovative analysis of the types of pathogens, various chemical forms of nitrogen and DBPs, and removal of these components during the recycling process, was related to season, climate and the four different treatment trains. It was concluded that the WWTP using a combined anaerobic/aerobic pond system was best at removing nitrogens and minimising DBP formation, but the best overall treatment performance was delivered by an activated sludge, oxidation ditch and infiltration pond WWTP in a temperate climate. Pathogens were found in influents but not treated effluents, and so were other nitrogen-removing micro-organisms. Treatment was better in summer, and the wastewater quality in these four WWTPs posed a low health and environmental risk to non-potable reuse.

Wastewater recycling uses reverse osmosis (RO) membranes to produce freshwater but this process also generates a waste stream – the reverse osmosis concentrate (ROC) – which contains almost all the contaminants present in the original wastewater. The disposal of untreated ROC poses a health and environmental risk. This research used 18 samples of ROC to test various treatment combinations and concluded that coagulation with ferric chloride followed by filtration with biological activated carbon reduced dissolved organic carbon, phosphorus and nitrogen compounds, and disinfection by-products, to safe and acceptable levels.

Recycling wastewater by using reverse osmosis (RO) and ultrafiltration appears to be associated with the formation of some groups of micropollutants but there is not much information about these processes. This research selected iodinated disinfection by-products (DBPs) and N-nitrosamines (NDMA), and benzotriazoles and benzothiazoles, which are compounds in dishwasher detergents, for further investigation. It was concluded that minimising the formation of dichloramine (a precursor molecule to NDMA formation) by reducing pH and maximising activated sludge ammonia production, reduced the formation of N-nitrosamines in RO-treated wastewater. Iodinated DBPs and benzotriazoles were detected in RO treated wastewater in this study but at lower concentrations than those thought to pose a risk to human health.

Fish, frogs, and other aquatic animals sometimes show signs of ‘endocrine disruption’; aberrant changes to their hormone or reproductive systems that are thought to be caused by chemicals in the water they inhabit. Very few of these chemicals have been identified, and this prevents the use of classical chemistry-based analytical methods. The other problem is that the levels of hormone-like chemicals which have endocrine-disrupting biological effects tend to be so low that standard chemical methods cannot detect them. This research developed a suite of biological tests sensitive enough to detect very low levels of chemicals associated with certain types of endocrine disruption. These tests were used to examine wastewater, surface water and drinking water collected from Australia, South Africa and four European countries. The water samples were also subjected to standard chemical analysis, and the datasets compared. It was concluded that some wastewater and surface water samples contained compounds that interacted with components of the estrogen, progesterone, androgen and mineralocorticoid hormone systems, but none of the biological tests detected endocrine disrupting activity in drinking water.

Some wastewater treatment plants (WWTPs) use membrane bioreactors (MBR). These contain a microporous membrane which clarifies treated wastewater by removing microbial organisms. Wastewater must also be treated to remove nitrogen and phosphorus, which can act like uncontrolled fertilisers if they are released to the environment. Iron or aluminium salts added to the wastewater react with phosphorus and make solid particles which can be ‘caught’ and separated in the MBR. The problem is that the amounts of iron salts commonly added to some WWTPs foul the membrane and reduce its performance. This research used a laboratory-scale MBR to discover that lower amounts of specific iron salts effectively reduce phosphorus to levels that are safe to discharge while also reducing fouling and increasing the operating life of the membrane. Another conclusion was that ascorbic acid (vitamin C) cleaned iron-associated foulants from membranes more effectively than the conventional cleaning agent, citric acid.

Reverse osmosis (RO) is used to desalinate seawater and brackish groundwater, and to remove microscopic pathogens from treated wastewater. The salty water is pressurised on one side of the RO membrane and this is part of the process that results in water molecules passing (diffusing) through the membrane to the lower pressure solution on the other side. Salts such as sodium chloride (table salt) and calcium sulphate and calcium carbonate (scale) do not diffuse easily across the RO membrane and build up on the high-pressure side. Eventually scale deposition on the membrane prevents the diffusion of water molecules and the production of freshwater declines. This research tested four commercial and three in-house antiscalent chemicals, and additionally developed a technique to monitor scale formation and RO membrane performance in real-time. It was concluded that the antiscalent ‘PC-191T’ was best and that adding an ‘Electrical Impedance Spectroscope’ to RO systems has the potential to deliver a sensitive in-situ, real-time monitoring method capable of detecting very early scale formation, well before membrane performance declines. This will enable optimisation of membrane scale removal and improve the efficiency of freshwater production.

Harmful pathogens and compounds must be removed from wastewater before it can be discharged to the environment or used for irrigation, and many source waters need salts removed to make them potable. Microfiltration and ultrafiltration membranes remove pathogens and unwanted chemicals but as they are used, they become fouled and blocked by particulates and compounds from the water being filtered, as well as by the formation of biofilm, and by chemical interactions between solutes and the membrane materials. Although the membranes are cleaned regularly, the cleaning chemicals themselves can cause a problem. This research characterised the damage that various cleaning regimens inflict on membranes made of different materials and examined the effects of progressive and consecutive stages of membrane aging and degradation on performance. It was concluded that the type of cleaning agent affects the mechanism of membrane degradation and the severity of membrane integrity loss. More information is needed regarding the cleaning protocols and agents used in industry. Information from this research can inform a generally applicable model to predict membrane aging and decline in performance.